Cleaning compositions containing a strong mineral acid such as hydrochloric acid are known.
U.S. Pat. No. 3,793,221 to Otrhalek describes a concentrate composition comprising 15-40% of aqueous HCl; 1-6% of an organic acid selected from oxalic, tartaric and citric acids; 7-23% nonionic surfactant; and 76-24% water. The sum of the amounts of surfactant is from 10-30% by weight of the composition, and the nonionic surfactant is about 75-90% by weight of the total surfactants. For use, the concentrate of this patent is diluted with from 1-5 parts water.
U.S. Pat. No. 4,032,466 also to Otrhalek discloses acid cleaning concentrates similar to the compositions of the '221 patent but also containing 1-12% of a flocculating agent. The water content varies from 75-12%.
U.S. Pat. No. 4,749,508 to Cockrell, Jr. et al discloses an acidic floor cleanser in ready to use concentrate form comprising 1-6% of an acid having a pKa value greater than 2.8 at 25.degree. C.; typically, citric, tartaric, malic, acetic, glycolic or gluconic acids. Additionally, the compositions contain 0.1-15% of an acid such as sulfuric, phosphoric, hydrochloric, or nitric acid with a pKa value of less than 2.5 at 25.degree. C. together with sufficient buffering salt to provide a composition having a pH of 1-6. The composition may also contain a surfactant, fumed silica or other selected ingredients.
Schmidt et al in U.S. Pat. No. 3,443,492 discloses a process for cleaning evaporation tubes with a mixture of an organic acid and a mineral acid. The former is utilized in an amount of from 20-40% by weight of the total acid in the composition.
U.S. Pat. No. 3,218,260 to Lewandowski discloses a cleaning composition comprising an acid in combination with an anionic surfactant which is an ethoxylated hydrophobic base, the agent containing at least 10 moles of ethylene oxide per mole of the base. The compositions of the patent are said to be characterized by good clarity in water.
U.S. Pat. No. 4,409,525 to Dodge discloses an etchant comprising a strong acid, a weak organic acid, and a water miscible solvent. A characteristic of the compositions of this invention is that they contain a minimum amount of water, i.e. less than 30% by weight.
Martucci, in U.S. Pat. No. 4,675,120 discloses compositions containing controlled amounts of hydrogen ion, the availability of which is maintained by combining strong and weak acid pairs.
Aqueous glass cleaning compositions are disclosed in U.S. Pat. No. 4,477,364 to have a pH of less than 1 and contain 1-13%, HF together with 85-99% mineral hydrocarboxylic or dicarboxylic acid.
Commercial, floor cleaning products are also known. One such composition is SURE TRAC sold by the Drackett Company. The composition is an aqueous mixture containing an anionic and a nonionic surfactant together with hydrochloric and glycolic acids, and is typically used after dilution with water.
Compositions such as SURE TRAC are excellent floor degreasers and are especially useful for quarry tile and concrete floors often provided in large food dispensing operations such as fast food restaurants. Although the ready-to-use aspect of such products is advantageous, they suffer the disadvantage that they contain large amounts of water. The high proportions of water adds to the cost of shipping and warehousing. Concentrates, on the other hand, although less expensive than ready-to-use compositions are often times not satisfactory because of a tendency to phase out on storage or when subjected to temperature stress. Moreover, the manufacture and bulk storage of the concentrate and before its final packaging for customer use is difficult in view of the tendency of the concentrate to separate on standing. In many instances once separation has occurred, it is difficult if not impossible to reconstitute and reobtain the properties of the original composition, especially viscosity.
Accordingly, it is an object of this invention to provide floor cleaning concentrates which do not suffer the disadvantages of the high water content compositions and have good storage stability, even under temperature stress.